Ensure MongoClient#close only actions on first call

Backport from: e069cfc

JAVA-4215

Author: rozza

driver-async/src/main/com/mongodb/async/client/MongoClientImpl.java

@@ -39,6 +39,7 @@
 import java.io.IOException;
 import java.util.Collections;
 import java.util.List;
+import java.util.concurrent.atomic.AtomicBoolean;
 
 import static com.mongodb.assertions.Assertions.notNull;
 import static com.mongodb.internal.async.ErrorHandlingResultCallback.errorHandlingCallback;
@@ -55,6 +56,7 @@ class MongoClientImpl implements MongoClient {
     private final ClientSessionHelper clientSessionHelper;
     private final CodecRegistry codecRegistry;
     private final Crypt crypt;
+    private final AtomicBoolean closed;
 
     MongoClientImpl(final MongoClientSettings settings, final Cluster cluster, @Nullable final Closeable externalResourceCloser) {
         this(settings, cluster, null, externalResourceCloser);
@@ -79,6 +81,7 @@ private MongoClientImpl(final MongoClientSettings settings, final Cluster cluste
         }
         this.externalResourceCloser = externalResourceCloser;
         this.codecRegistry = createRegistry(settings.getCodecRegistry(), settings.getUuidRepresentation());
+        this.closed = new AtomicBoolean();
     }
 
     @Override
@@ -113,16 +116,18 @@ public MongoDatabase getDatabase(final String name) {
 
     @Override
     public void close() {
-        if (crypt != null) {
-            crypt.close();
-        }
-        serverSessionPool.close();
-        cluster.close();
-        if (externalResourceCloser != null) {
-            try {
-                externalResourceCloser.close();
-            } catch (IOException e) {
-                LOGGER.warn("Exception closing resource", e);
+        if (!closed.getAndSet(true)) {
+            if (crypt != null) {
+                crypt.close();
+            }
+            serverSessionPool.close();
+            cluster.close();
+            if (externalResourceCloser != null) {
+                try {
+                    externalResourceCloser.close();
+                } catch (IOException e) {
+                    LOGGER.warn("Exception closing resource", e);
+                }
             }
         }
     }

driver-legacy/src/main/com/mongodb/Mongo.java

@@ -57,6 +57,7 @@
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Executors;
 import java.util.concurrent.ScheduledExecutorService;
+import java.util.concurrent.atomic.AtomicBoolean;
 
 import static com.mongodb.ReadPreference.primary;
 import static com.mongodb.client.internal.Crypts.createCrypt;
@@ -104,6 +105,7 @@ public class Mongo {
     private final ConcurrentLinkedQueue<ServerCursorAndNamespace> orphanedCursors = new ConcurrentLinkedQueue<ServerCursorAndNamespace>();
     private final ExecutorService cursorCleaningService;
     private final MongoClientDelegate delegate;
+    private final AtomicBoolean closed;
 
     /**
      * Creates a Mongo instance based on a (single) mongodb node (localhost, default port)
@@ -332,6 +334,7 @@ public Mongo(
                 autoEncryptionSettings == null ? null : createCrypt(asSimpleMongoClient(), autoEncryptionSettings));
 
         cursorCleaningService = options.isCursorFinalizerEnabled() ? createCursorCleaningService() : null;
+        this.closed = new AtomicBoolean();
     }
 
     // bit of a hack, but it works because only MongoClient subclass will ever make use of this
@@ -555,9 +558,11 @@ public void dropDatabase(final String dbName) {
      * databases obtained from it can no longer be used.
      */
     public void close() {
-        delegate.close();
-        if (cursorCleaningService != null) {
-            cursorCleaningService.shutdownNow();
+        if (!closed.getAndSet(true)) {
+            delegate.close();
+            if (cursorCleaningService != null) {
+                cursorCleaningService.shutdownNow();
+            }
         }
     }
 

driver-sync/src/main/com/mongodb/client/internal/MongoClientDelegate.java

@@ -48,6 +48,7 @@
 
 import java.util.ArrayList;
 import java.util.List;
+import java.util.concurrent.atomic.AtomicBoolean;
 
 import static com.mongodb.MongoException.TRANSIENT_TRANSACTION_ERROR_LABEL;
 import static com.mongodb.MongoException.UNKNOWN_TRANSACTION_COMMIT_RESULT_LABEL;
@@ -66,6 +67,7 @@ public class MongoClientDelegate {
     private final OperationExecutor operationExecutor;
     private final Crypt crypt;
     private final CodecRegistry codecRegistry;
+    private final AtomicBoolean closed;
 
     public MongoClientDelegate(final Cluster cluster, final CodecRegistry codecRegistry, final List<MongoCredential> credentialList,
                                final Object originator, @Nullable final Crypt crypt) {
@@ -82,6 +84,7 @@ public MongoClientDelegate(final Cluster cluster, final CodecRegistry codecRegis
         this.originator = originator;
         this.operationExecutor = operationExecutor == null ? new DelegateOperationExecutor() : operationExecutor;
         this.crypt = crypt;
+        this.closed = new AtomicBoolean();
     }
 
     public OperationExecutor getOperationExecutor() {
@@ -127,11 +130,13 @@ public List<ServerAddress> getServerAddressList() {
     }
 
     public void close() {
-        if (crypt != null) {
-            crypt.close();
+        if (!closed.getAndSet(true)) {
+            if (crypt != null) {
+                crypt.close();
+            }
+            serverSessionPool.close();
+            cluster.close();
         }
-        serverSessionPool.close();
-        cluster.close();
     }
 
     public Cluster getCluster() {